<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Document</title>
  <style></style>
</head>

<body>
  <div id="app">
    <div>
      <p>请选择你要购买的书籍</p>
      <ul>
        <li v-for="(inex,id) in arr">
          <p>{{inex.name}} <button @click="txt(id)">购买</button></p>

        </li>
      </ul>
      <table border="1" width="500" cellspacing="0">
        <tr>
          <th>序号</th>
          <th>书名</th>
          <th>单价</th>
          <th>数量</th>
          <th>合计</th>
        </tr>
        <tr v-for="(inex,id) in arr">
          <th>{{id+1}}</th>
          <th>{{inex.name}}</th>
          <th>{{inex.price}}</th>
          <th>{{inex.count}}</th>
          <th>{{inex.price*inex.count}}</th>
        </tr>
      </table>
      <p>总价格为:{{zongjia}} </p>
    </div>
  </div>
  <script src="../vue.js"></script>
  <script>
    const app = new Vue({
      el: "#app",
      //定义属性
      data: {
        arr: [
          {
            name: "水浒传",
            price: 107,
            count: 0,
          },
          {
            name: "西游记",
            price: 192,
            count: 0,
          },
          {
            name: "三国演义",
            price: 219,
            count: 0,
          },
          {
            name: "红楼梦",
            price: 178,
            count: 0,
          },
        ],
        zongjia: 0
      },
      //定义方法
      methods: {
        txt(id) {
          this.arr[id].count++
        }
      },
      watch: {
        arr: {
          deep: true,
          immediate: true,
          handler(newValue) {
            this.zongjia = this.arr.reduce(function (pre, inex) {
              return inex.price * inex.count + pre
            }, 0)
          }
        }
      }
    });
  </script>
</body>

</html>